Millimeter-wave phased-array radio front-ends in SiGe BiCMOS technologies

This thesis presents the design and implementation of state of the art phased-array millimeter-wave front-ends in SiGe BiCMOS technology. After reviewing the basic operation principles of phased-array systems with a focus on wireless communication, the linearity of the phased-array receivers is analyzed, to understand the effects of the phase shifter linearity on the overall system performance. Different types of millimeter-wave phase shifters are presented, then the vector-modulator is studied in details from the system level performance to circuit design and optimization. Finally, a design procedure of millimeter-wave vector-modulators is proposed. Then, it is used to design high resolution 60 GHz vector-modulator and the first reported 240 GHz vector modulator. 60 GHz phased-array transmitter and receiver front-ends fabricated in 0.25 μm SiGe BiCMOS technology are presented afterwards. The transmitter features 2-bit 60 GHz phase shifters. The receiver contains a 60 GHz vector-modulator which is capable of 360◦ of phase shift and 20 dB amplitude control. A 240 GHz chip-to-chip communication system is introduced. System level analysis and link budget showed that phased-arrays are indispensable for such high frequencies. The design of the first reported Butler matrix phased-array front-end operating above 180 GHz is then discussed, followed by the design of the 240 GHz vector-modulator based front-end. Furthermore, the design of modulators and demodulators operating at 240 GHz is presented.